1. Field
The present disclosure relates to a control device for an internal-combustion engine and a control method for an internal-combustion engine.
2. Description of the Related Art
Hitherto, a control device for an internal-combustion engine described in Japanese Unexamined Patent Application Publication No. 2005-155506 has been known. This internal-combustion engine includes a variable compression ratio mechanism that changes the compression ratio of the internal-combustion engine, and a turbocharger that can change the supercharging pressure. This control device controls the compression ratio of the internal-combustion engine by a control method shown in FIG. 4 of the same publication.
That is, first, a target load, a steady-state reach supercharging pressure, and a supercharging delay time constant are calculated in accordance with the accelerator opening degree and the engine speed. Then, an estimated supercharging pressure is calculated by using the steady-state reach supercharging pressure and the supercharging delay time constant with a primary delay arithmetic expression, and an actual load is calculated on the basis of the target load, the steady-state reach supercharging pressure, and the estimated supercharging pressure. Also, a target compression ratio is calculated in accordance with the actual load and the engine speed to prevent a knocking from occurring, and the compression ratio of the internal-combustion engine is controlled to meet the target compression ratio through the variable compression ratio mechanism.